In the manufacture of large commercial aircraft as well as other similar large mechanical assemblies, various parts of the assemblies are secured together with bolts, typically lock bolts, with collar members being swaged on to the ends of the bolts for secure attachment of the parts. Typically, the collar members, which are small hollow cylindrical sections of appropriate internal diameter relative to the bolt, sometimes having a flange, are moved from a storage unit such as a bin or a cartridge, to the exposed end of the bolt, which extends through registered openings in the two parts (workpieces) to be joined, which have been previously clamped together.
After the collar is moved onto the exposed end of the bolt, it is swaged thereon for secure attachment of the clamped workpieces. In this process, collars are typically delivered to a collar gripper assembly which positions the collar in alignment with the end of the bolt and the swaging die. Such systems are commonly used throughout the industry. Two examples are shown in U.S. Pat. No. 6,253,448 and U.S. Pat. No. 5,437,094, both of which are owned by the assignee of the present invention. Collar gripper systems have various configurations, depending upon the configuration of the collar and the two parts to be joined. In some cases, collars are delivered directly on a straight line to the end of the bolt, while other systems involve an offset arrangement, because one part has a configuration which prevents a straight line collar delivery path.
One commercial collar feed system using a gripper apparatus is shown in FIGS. 1A and 1B. This system includes a feed tube 11 in which a collar 11a is fed with its longitudinal opening parallel with the direction of the feed tube. A pivoting collar gripper member 11b grips the collar as it exits from the feed tube and then pivots the collar into position, as shown in FIG. 1B, at which point a bolt 11c is driven through the collar. The gripper is then retracted and the collar is swaged onto the bolt with a swaging die by action of the ram 11d, in well-known, conventional fashion. In this system, the gripper and the swaging die must be accurately aligned with the opening in the workpiece through which the bolt extends.
Another commercial product is shown in FIGS. 2A and 2B. In this system, a collar 13a is delivered through a feed tube 13, with the collar opening being perpendicular to the length of the feed tube. The collar is fed to a collar gripper 13b, which grips the exterior surface of the collar, moves the collar upwardly, into a position where the tool die 13c picks up the collar 13 and, following retraction of the gripper 13b, moves the collar onto a bolt 13d, where it is swaged in well-known, conventional fashion.
These known collar gripper systems are, however, often complex, expensive and can wear out or break. Also, each size of collar, and there are typically several different sizes used on a particular aircraft or other large scale assembly, require different collar gripper systems and an associated swaging system. Another disadvantage to gripper systems in general is the difficulty in accurately aligning the bolt, the collar and the die. Even small misalignments can result in a collar attempting to move onto a bolt in a tipped orientation, causing difficulties in the swaging process and/or delays in manufacturing due to the necessity of removing a damaged or misaligned collar, which is time-consuming.
Hence, a system by which a collar can be accurately delivered to placement on the bolt used in manufacture of large scale mechanical assemblies, while maintaining accurate alignment between the bolt, the collar and the die, without the disadvantages of a collar gripping system, would be a significant advantage over existing gripping systems.